Abstract: Experimental research on the flow characteristics of boiling two-phase liquid sodium in an annuli was done. Experimental conditions were G≤2000 kg•m²•s^-1, p≤0.1 MPa and q≤550 kW•m^-2. Two-phase frictional multiplier was calculated to investigate the boiling two-phase friction pressure drop. The experimental results show that the two-phase frictional multiplier decreases with the increase of the Martinelli parameter. On the base of the data of this work, Lurie et al.’s data and Kaiser et al.’s data, a correlation of the two-phase frictional multiplier for liquid sodium boiling in an annuli was obtained. RSD was used to evaluate the applicability of this correlation to the liquid sodium boiling in an annuli. It shows that this correlation is suitable for the flow characteristics of liquid sodium boiling in an annuli.